1. Field of the Invention
The present invention relates in general to the field of information handling system storage, and more particularly to a system and method for information handling system redundant storage rebuild.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
As information handling systems have become increasingly prevalent in enterprises and homes, they have generated tremendous amounts of information for storage and subsequent access. For example, businesses maintain customer, accounting, inventory, research, product design and other critical types of information. As another example, individuals maintain personal financial information, pictures, videos and other important personal information. In order to protect important information from disappearing in the event of a storage failure, enterprises and individuals often use redundant storage techniques. One such category of redundant storage techniques is the use of a redundant array of independent disks (RAID). Although a variety of RAID configurations exists, a typical RAID array combines multiple hard disk drives into LUNs that distributes a copy of information stored on any one hard disk drive to at least one other hard disk drive of the array so that a redundant copy of all information in the array exists for use in the event of a hard disk drive failure. To accomplish such redundancy, each hard disk drive is divided into fixed-size stripe units made of several disk sectors, such as units of 8 KB to 256 KB of storage. A parity map maintains a relationship between these units to track where the units are stored on different hard disk drives. After a failure occurs at a hard disk drive, the information stored on the failed hard disk drive is regenerated from the parity data and written to a replacement hard disk drive.
One difficulty with recreating a failed hard disk drive on replacement hard disk drive is that the data reconstruction operation, also known as an XOR operation, is time consuming and must include several I/O's made to all disk units of the array during the rebuild process. Since the rebuild process for servicing Input/Output (I/O) uses both a rebuild pointer and rebuild status for each region, these parameters must be maintained during the rebuild. During a rebuild process, a RAID controller performs the data reconstruction operation by rebuilding each logical unit starting with a first logical block of the failed hard disk drive and proceeds sequentially to the last logical block with I/O regeneration happening at the granularity of stripe element size. The result of a conventional rebuild process is an identical drive, however reconstructing the data with XOR operations is very time consuming and the overhead associated with the sequential XOR operations can slow overall system performance. For example, one typical 1TB replacement drive re-creation took 16 hours to complete. Until the failed drive is re-created, failure of another hard disk drive within the same array can result in permanent loss of information. Some steps can result in reduced rebuild time, such as avoiding rebuild of portions of the failed drive that did not save data, however, performing the XOR calculations to rebuild the remaining portions of the drive still consumes time and resources.
Due to increased time to rebuild, the LUN is susceptible to subsequent hard disk drive failure. Hence there is a need to reduce the overall time taken to rebuild a failed drive of a RAID array at a replacement drive.